A simple way to do something like that in an IIS based web if you know a little about sql..
Create a database with an "ID"(set as primary key / auto-number), "Date" (with an auto date/time default value), and "Bookmark" field and create an ODBC system DSN for that database. Create an asp page that on load inserts a new record into that database with a value like "x" or something for the bookmark field. So you only need one page, on the same page do an sql statement "SELECT LAST(ID)+1 FROM tablename" and tack your @mydomain.com to the end of the results displayed on the page. When the page is loaded it will create a new record in the database and spit out an email address on the page with the "(ID field value)@yourdomain.com" on the page.
When you receive an e-mail sent to #@yourdomain.com, look up that number in your database then look for a hit in your web server log at exactly the same time/date. [text was edited by author 2002-02-20 21:01:05]
Here's the asp page created in FrontPage and the database assuming you have a a system dsn called "log" set up in ODBC and you set up a connection to it in FrontPage or in your global.asa [text was edited by author 2002-02-20 21:18:47]
That's a really good idea! You could also put (with server side scripting) the users' IP, machine name, user name.. all kinda good stuff.
What would also be great is to setup a little SMTP service to accept incomming mail (not do anything with it). You'ld need a service though to monitor the 'drop' folder of the mail service for messages addressed to your specially created addresses and notify you of when something has been address to one.
You'ld know who it was, when they snaked the address... but, the spam could be sent out days after the mail address was collected...